What is it? A 9 level tower of black “marble” stone. Interior features with familiar SW elements including iron/steel/laen tracked doors, glowing glass panels. There is even a lower level cavern hall.
How and where to use it in Shadow World? The tower feels A LOT like the Loremaster’s Tower of the Winds with its High Council Chamber and the lower cavern could be the repository for the Master Orb. (MA p.72). But the elements, materials and craftsmanship certainly evoke LoE or 2nd Era style.